The toy POST example keeps its boundary narrow.
What this toy model checks
The trust boundary parses one POST request, splits headers from body, counts bytes, and splits the pinned ASCII form body.
recompute POST rows \text{recompute POST rows} recompute POST rows POST honesty boundary The body bytes, parsed fields, and length check are recomputed from pinned POST bytes. POST honesty boundary - POST /submit body 7 bytes, fields a=1 and b=2 section name value check request line method POST parsed request line path /submit parsed request line version HTTP/1.1 parsed header Host forms.example exact header Content-Type application/x-www-form-urlencoded form encoding header Content-Length 7 declared bytes body display words a=1 ampersand b=2 safe display form body exact hex 613d3126623d32 pinned bytes body byte length 7 counted field a a=1 parsed field b b=2 parsed check Content-Length 7 declared check body bytes 7 recomputed check match yes same count
Honesty boundary
NOTE: toy HTTP POST form only; not multipart forms, file upload, URL decoding beyond the pinned ASCII body, repeated keys, character sets, validation, CSRF, authentication, browser form behavior, server frameworks, streaming, chunked transfer, or production security config.
toy POST form only \text{toy POST form only} toy POST form only POST honesty boundary The body bytes, parsed fields, and length check are recomputed from pinned POST bytes. POST honesty boundary - POST /submit body 7 bytes, fields a=1 and b=2 section name value check request line method POST parsed request line path /submit parsed request line version HTTP/1.1 parsed header Host forms.example exact header Content-Type application/x-www-form-urlencoded form encoding header Content-Length 7 declared bytes body display words a=1 ampersand b=2 safe display form body exact hex 613d3126623d32 pinned bytes body byte length 7 counted field a a=1 parsed field b b=2 parsed check Content-Length 7 declared check body bytes 7 recomputed check match yes same count
No client compute
The page shows already validated rows. It does not parse form data in browser code.
static validated rows \text{static validated rows} static validated rows POST honesty boundary The body bytes, parsed fields, and length check are recomputed from pinned POST bytes. POST honesty boundary - POST /submit body 7 bytes, fields a=1 and b=2 section name value check request line method POST parsed request line path /submit parsed request line version HTTP/1.1 parsed header Host forms.example exact header Content-Type application/x-www-form-urlencoded form encoding header Content-Length 7 declared bytes body display words a=1 ampersand b=2 safe display form body exact hex 613d3126623d32 pinned bytes body byte length 7 counted field a a=1 parsed field b b=2 parsed check Content-Length 7 declared check body bytes 7 recomputed check match yes same count
Summary
A POST request can carry small form fields in its body bytes.
body carries fields \text{body carries fields} body carries fields POST honesty boundary The body bytes, parsed fields, and length check are recomputed from pinned POST bytes. POST honesty boundary - POST /submit body 7 bytes, fields a=1 and b=2 section name value check request line method POST parsed request line path /submit parsed request line version HTTP/1.1 parsed header Host forms.example exact header Content-Type application/x-www-form-urlencoded form encoding header Content-Length 7 declared bytes body display words a=1 ampersand b=2 safe display form body exact hex 613d3126623d32 pinned bytes body byte length 7 counted field a a=1 parsed field b b=2 parsed check Content-Length 7 declared check body bytes 7 recomputed check match yes same count